Bases:
• Are planar
• Helps with base stacking
• Stabilises the double strands
• Purine: Adenine, Guanine
• Pyrimidines: Thymine (found only in DNA but in RNA it is
replaced by Uracil), cytosine
What are heterocyclic bases?
There are four heterocyclic bases in DNA: adenine (A), guanine (G), cytosine (C) and thymine (T).
A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two
different elements as members of its ring(s).
, Sugars
Bonding of nitrogenous bases to sugar
N-glycosidic bonds, have the glycosidic bond oxygen replaced with nitrogen.
Between PURINE and sugar is a N-9, Beta-N glycosidic bond
Between PYRIMIDINE and Sugar is a N-1, Beta-N glycosidic bond
Substances containing N-glycosidic bonds are also known as glycosylamines. Nucleosides are
Glycosylamines.
Phosphate Group
Essential for nucleotide polymerization
Important in nomenclature of nucleotides:
• No. of phosphate groups determine this: Eg:
AMP (Adenosine Diphosphate), ADP
(Adenosine Diphosphate) and ATP
(Adenosine Triphosphate)
Pyrophosphates (PPi) – Formed during hydrolysis of
ATP to cAMP with enzyme Adenyl cyclase
When the bond between 2nd and third phosphates
(2nd and third from 5' end) broken it releases one
phosphate group. We call it an inorganic phosphate
group.
If the bond between first and second phosphate
groups broken two phosphates groups (attached as a
single group) is released, we call it a pyrophosphate
group.
Both orthophosphate and pyrophosphate form
resonance structures and are stable at their forms not the "triphosphate" without the sugar part.
• Are planar
• Helps with base stacking
• Stabilises the double strands
• Purine: Adenine, Guanine
• Pyrimidines: Thymine (found only in DNA but in RNA it is
replaced by Uracil), cytosine
What are heterocyclic bases?
There are four heterocyclic bases in DNA: adenine (A), guanine (G), cytosine (C) and thymine (T).
A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two
different elements as members of its ring(s).
, Sugars
Bonding of nitrogenous bases to sugar
N-glycosidic bonds, have the glycosidic bond oxygen replaced with nitrogen.
Between PURINE and sugar is a N-9, Beta-N glycosidic bond
Between PYRIMIDINE and Sugar is a N-1, Beta-N glycosidic bond
Substances containing N-glycosidic bonds are also known as glycosylamines. Nucleosides are
Glycosylamines.
Phosphate Group
Essential for nucleotide polymerization
Important in nomenclature of nucleotides:
• No. of phosphate groups determine this: Eg:
AMP (Adenosine Diphosphate), ADP
(Adenosine Diphosphate) and ATP
(Adenosine Triphosphate)
Pyrophosphates (PPi) – Formed during hydrolysis of
ATP to cAMP with enzyme Adenyl cyclase
When the bond between 2nd and third phosphates
(2nd and third from 5' end) broken it releases one
phosphate group. We call it an inorganic phosphate
group.
If the bond between first and second phosphate
groups broken two phosphates groups (attached as a
single group) is released, we call it a pyrophosphate
group.
Both orthophosphate and pyrophosphate form
resonance structures and are stable at their forms not the "triphosphate" without the sugar part.
